Most consumers probably know it better as the "Shot on iPhone" campaign — having seen one of Apple's 10,000+ billboards across 25 countries showcasing the amazing photographs real people managed to shoot on their iPhones. The photos also appeared across newspapers, magazines, online, and in a set of 15-second TV commercials.

The campaign returns: This "Shot on iPhone 6s" billboard was spotted in Shoreditch, London.Business Insider

It's a really simple idea, and the creative is even simpler: A photo taken using the iPhone 6; shot by both amateurs and professionals; discovered using one of the many online photo-sharing platforms such as Instagram and Flickr; the "Shot on iPhone 6" tagline; and the name of the photographer.

Apple and its agency said the first round of the campaign was seen at least 6.5 billion different times, mentioned by 24,000 "opinion leaders," and that 95% of the mentions about the campaign online were positive.

Juan Carlos Ortiz, creative chairman of the DDB Americas ad agency network and the president of the Cannes Lions outdoor award jury, told Business Insider the jury "did not choose the campaign — the campaign chose us."

One of the image's used in last year's "World Gallery" billboards.Apple

"We had some really good finalists but the great part of this campaign was that it was more than a great creative idea. This is a game-changer," Ortiz said. "The idea was that it was open to people. You can ake a photo with your iPhone 6 and it could go up on a billboard all over the world. It wasn't just about taking a picture, it's that your picture can be displayed in the most exciting places in the world. It was about arming people with a real opportunity to take part in something big."

Another of the images being used in this year's "World Gallery" campaign.Apple

From its famous "1984" Super Bowl ad, Apple has a history of producing ads that don't just show off product benefits, but are wider cultural pieces, explained Ortiz. The "World Gallery" became just that — a huge global gallery of work that even saw art fans embarking on a sort of treasure hunt, tagging pictures of themselves when they saw sightings of the billboards.

Thomas Husson, vice president and principal analyst at Forrester Research, told Business Insider the campaign is really well-aligned to Apple's DNA: "It is all about lifestyle, imagination, liberty regained, innovation, passion, and power-to-the-people through technology."

It worked so well because it coupled human emotion with actual product benefits, rather than product features. Husson said: "In this particular campaign, it is really about what the iPhone enables: the ability to merge social offline experiences with online communications and to deliver more expressive and emotional forms of communications."

An award-winning ad campaign that turned into a cultural moment, shared by tens of thousands of people: It's little wonder Apple is running the push a second time around.